stylus has the same problem. I had to go to the previous version of stylish although it goes back to the update even though I check as default.

Fix problems that block programs from being installed or removedSelect the Download button on this page.In the File Download dialog box, click Run or Open, and then follow the steps in in the Program Install and Uninstall Troubleshooter.

That is not the problem. The problem is whenever I want to install something I click on install nothing happens.

"The new stylish won't install custom themes."New Stylish (and Stylus) won't work in Firefox 52 (or in SeaMonkey or Cyberfox, which are built on Firefox 52) even though you can install it. The new extensions use features that Firefox 52 didn't have. They may not work in your Comodo Dragon (built on Firefox 57) for the same reason.

"The new stylish won't install custom themes."New Stylish (and Stylus) won't work in Firefox 52 (or in SeaMonkey or Cyberfox, which are built on Firefox 52) even though you can install it. The new extensions use features that Firefox 52 didn't have. They may not work in your Comodo Dragon (built on Firefox 57) for the same reason.

In fact you're posting here with Firefox 60 in Windows 7; nevertheless, Stylish should be working. (1) Open the Browser Console (ctrl+shift+j), write a new global style with this as the CSS content: * { color: red !important; }save it, and enable it. (2) Copy+paste the Browser Console into a text file and attach it to a message that says whether or not the style worked, which browser and version you used (in about:support), and which extension and version you used (in about:addons).

Then (3) go to https://userstyles.org/styles/1 and click 'Install', (4) copy+paste from Browser Console into a text file and attach it to a message describing exactly what you saw happen -- every dialog box, every message, everything.

... Oh, and I see that Jefferson was using Firefox 56 when he replied to you, so Stylus should have working in your Comodo browser (Firefox 57).